1. Field of the Invention
The present invention relates to a drowsiness alarm apparatus and, more specifically to an alarm apparatus and program for reducing the possibility of an incorrectly issued alarm.
2. Description of the Related Art
A conventional drowsiness alarm apparatus including a photographic means, a wakefulness estimate means, and an alarm means is known. The photographic means sequentially photographs a driver's face. The wakefulness estimate means processes an image photographed, acquired, or otherwise captured by the photographic means and estimates the wakefulness degree of the driver. The alarm means generates an alarm assuming that the driver feels drowsy when the wakefulness estimate means estimates a wakefulness degree to be low.
Such a drowsiness alarm apparatus sequentially calculates an opening degree of an eye of the driver based on the photographed image and, for example, on a distance between upper and lower eyelids, which can be referred to hereinafter as an opening degree value, obtained from the image. The apparatus accumulates the calculated opening degree values at a predetermined time interval and calculates an accumulated value. When the accumulated value is less than or equal to a specified value, the apparatus determines the wakefulness state to be low as described for example, in JP-1995-181012A.
Disadvantages become apparent with such as system however in that a driver who expresses emotions while driving a vehicle may change the degree of eye opening. Depending on the emotion, the opening degree value may become smaller than the normal opening degree value that is present when the wakefulness degree is high and no emotion is expressed. For example, a smile will tend to narrow the eye opening and decrease the opening degree value. In such a situation, a conventional drowsiness alarm apparatus may incorrectly assume the driver to be drowsy and issue an alarm simply because the emotion is expressed.